Mass spectral analysis of N-oxides of nitrogen mustards, and N,N-dialkylaminoethyl-2-chlorides under electrospray ionization conditions

Chemical weapons convention (CWC) includes verification of chemical warfare agents and their precursors/degradation products in various environmental matrices. Nitrogen mustards and N,N-dialkylaminoethyl-2-chlorides, the precursors for the synthesis of nerve agents (VX type of compounds), are prone to undergo oxidation in environmental matrices or during decontamination process. Thus, screening of the oxidized products of the CWC related compounds is also an important task in the verification process. Here we report the successful characterization of the N-oxides of nitrogen mustards and N,N-dialkylaminoethyl-2-chlorides under positive ion electrospray ionization tandem mass spectrometry conditions. The collision-induced dissociation spectra of [M+H]+ ions show distinct product ions that enable unambiguous identification of studied N-oxides, including those of isomeric compounds. The proposed fragmentation pattern of these compounds is based on isotopic abundance ratio, high-resolution mass spectrometry data and product/precursor ion spectra. The CID spectra of [M+H]+ ions of the studied compounds include a specific product ion, [MH−(OH + CH2Cl)]+, and distinctive alkene losses to recognize the attached alkyl group to the nitrogen.

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► Verification of CWAs and their degradation products is important for CWC.
► The Nitrogen mustards (NMs) undergo N-oxidation during decontamination process.
► N-oxides of NMs can be used as the markers for alleged use or production of NMs.
► N-oxides of the NMs and dialkyl aminoethyl-2-chlorides were analyzed by ESI-MS/MS.
► [MH−(OH + CH2Cl)]+ ion is characteristic to the studied N-oxides.